Isomerenspezifische Bestimmung der Polychlordibenzodioxine (PCDD) und Polychlordibenzofurane (PCDF)

Ohne Zusammenfassung

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Isomer-specific determination of the polychlorinated dibenzodioxins (PCDD) and polychlorinated dibenzofurans (PCDF)

     

Isomer-specific separation of 2,3,7,8-class congeners of polychlorodibenzodioxins and -dibenzofurans on a smectic liquid-crystalline stationary phase in capillary gas chromatography

A smectic liquid-crystalline stationary phase was used in high resolution gas chromatography for the analysis of the patterns of the chloro-homologues of the polychlorodibenzodioxins and polychlorodibenzofurans. Unique selectivity for most of the 2,3,7,8-class congeners was observed. Use of this phase as an alternative to cyanopropylsilicone phases in the isomer-specific analysis of halogenated and mixed halogenated dibenzodioxins and dibenzofurans is discussed.     

Automated clean-up procedure for the gas chromatographic-high-resolution mass spectrometric determination of polychlorinated dibenzo-p-dioxins and dibenzofurans in milk.

A highly automated extraction and clean-up method for polychlorinated dibenzodioxins and polychlorinated dibenzofurans is described. The method includes the use of gel permeation chromatography, alumina clean-up and porous graphitized carbon chromatography, followed by analysis by gas chromatography-high-resolution mass spectrometry. The procedure allows for the analysis of six milk samples per day in addition to two quality control samples and a blank. Detection limits on a fat basis for the individual congeners in milk samples are in the sub-ppt range. Long-term performance was investigated and data are given for reproducibility, precision and accuracy.     

Bestimmung von bromierten Dibenzofuranen, die bei der Thermolyse von Polymeren mit Decabromdiphenylether als Flammschutzmittel gebildet werden

Summary Several plastics (polyester and hardened epoxideresins) with flame retardants as additives were tested for the formation of brominated dibenzofurans and dibenzodioxins under temperatures from 400 °C to 800 °C under aerobic conditions. 2,3,7,8-Tetrabromodibenzodioxin was not formed at a detection limit of 10 ppm (g·g^–1). At 400 °C, polymers containing decabromodiphenylether and antimony trioxide as flame retardant yield up to 4,000 ppm tetrabromodibenzofurans (TBrDF), besides other brominated dibenzofurans.In contrast, formation of polybrominated dibenzofurans does not occur with polymers containing decabromodiphenylether without antimony trioxide. 2,3,7,8-Tetrabromodibenzufuran could not be found at a detection limit of 20 ppm. Under the given thermolytical conditions, polymers with brominated flame retardants such as tetrabromobisphenol-A, polytribromostyrene, hydroxyethylated tetrabromobenzimidazolone, poly(pentabromobenzyl)acrylate or N,N-ethylene-bis-tetrabromophthalimide snowed no tendency to form polybrominated dibenzodioxins or dibenzofurans, even in the presence of antimony trioxide.     

New strategy for comprehensive analysis of polybrominated diphenyl ethers,polychlorinated dibenzo-p-dioxins,polychlorinated dibenzofurans and polychlorinated biphenyls by gas chromatography coupled with mass spectrometry

A strategy for determination of polybrominated diphenyl ethers, polychlorinated dibenzodioxins, polychlorinated dibenzofurans and polychlorinated biphenyls on fatty matrices has been established. After extraction, the proposed method allows the purification and the fractionation of all target groups of compounds in a simple multi-step automated clean-up. Furthermore, their subsequent analysis is carried out using a single benchtop mass spectrometer, in four separate injections. Required sensitivity considering levels found in the environment is attained using electron impact ionisation followed by tandem in time mass spectrometry. The whole method has been evaluated on standard solution and quality control samples consisting of fortified beef fat. Sensitivity, selectivity, accuracy and repeatability were tested with satisfactory results.     

Sampling and analysis of flue gases from a plasma incinerator

A system is described for monitoring flue gases from a plasma incinerator for polychlorinated biphenyls (PCBs), polychlorinated dibenzodioxins and polychlorinated dibenzofurans. The system is composed of three basic units: sampler/preconcentrator, gas chromatograph and mass-selective detector. The sampler operates by solid sorbent trapping and thermal desorption. The use of two adsorbers allows sampling at a high flow rate (～1 1 min^?1) and subsequent capillary gas chromatographic analysis without the need for cold traps. A sample trapped on the first adsorber is thermally desorbed and transferred by a carrier stream of 40 cm³ min^?1 to a second smaller adsorber and retrapped. It is then thermally desorbed and injected into the capillary column by a carrier gas at an appropriate flow rate. A sequential valve-minder activates the electric actuators of the two six-port valves used in the design and also controls the power required for heating the adsorbers. Operation of the sampler is automated and is initiated by a single push-button switch. In simulation, the system allowed the separation of the major compounds of interest from possible interferences in <15 min and afforded unambiguous identification of the hazardous compounds and their quantification. For a sample volume of 20 1, the minimum detectable concentration of PCBs is 25–50 ng m^?3.     

Analysis of organic micropollutants in the lipid fraction of foodstuffs.

An overview is given of current techniques for the analysis of organic micropollutants that accumulate in the fatty fraction of foodstuffs, such as pesticides, polychlorinated biphenyls, polycyclic aromatic hydrocarbons, polychlorinated dibenzodioxins and polychlorinated dibenzofurans. Isolation and clean-up are considered to be of great importance in the field of residue analysis. In general, problems are related to the low levels of the individual compounds at which they usually occur and the complexity of extraction and clean-up procedures for isolating and separating analytes from matrix components and other contaminants. Therefore, special attention is focused on sample pretreatment and on coupled chromatographic techniques, showing developments towards multi-residue methods, miniaturization and automation of analytical procedures. Coupling of chromatographic techniques with spectroscopic techniques is also considered as an important tool for identification and confirmation purposes.     

Use of supercritical fluid extraction in the analysis of polychlorinated dibenzodioxins and dibenzofurans

Summary Supercritical fluid extraction is a powerful technique with great promise in organic analytical chemistry. To date little has been published on the use of SFE in the analysis of polychlorinated dibenzodioxins and dibenzofurans (PCDD/F). The data point, however, to the feasibility of a selective and exhaustive extraction of these compounds. Solid phase trapping of the extracted PCDD/F allows for on-line class separation and clean-up and seems to be the most flexible choice of collection mode. Both CO₂ and N₂O can be used as supercritical fluids. Extraction recoveries can be improved with a small percentage of an organic solvent added to the supercritical fluid as modifier. Methanol and benzene have proven to be efficient. Relatively strong supercritical fluid conditions are needed for the extraction of PCDD/F from fly ash (350–400 atm at 330–370 K). Spiked internal standards are easily extracted even at mild conditions whereas native PCDD/F are not; thus caution should be taken when an isotopic dilution technique is used for a future evaluation of SFE in the analysis of PCDD/F.     

Separation of polychlorinated dibenzothiophenes from polychlorinated dibenzodioxins and -furans

Polychlorinated dibenzothiophenes (PCDT) have recently been identified in a series of environmental samples. Since their masses are very close to those of the polychlorinated dibenzodioxins (PCDD), low resolution mass selective detection cannot be used to distinguish between these two classes of compounds. A method is presented which may allow this, involving the oxidation of the PCDTs to the corresponding sulfones which have a higher mass than the PCDDs. If needed, the PCDTO₂s can easily be separated from the PCDDs and the polychlorinated dibenzofurans (PCDFs) by simple chromatographic techniques. The PCDDs/Fs are apparently stable under the oxidative conditions so that now a determination of PCDDs and PCDFs becomes possible without interference from PCDTs.     

Quantum Chemical Investigation of Polychlorinated Dibenzodioxins,Dibenzofurans and Biphenyls: Relative Stability and Planarity Analysis

All the possible polychlorinated aromatic compounds in the classes of dibenzodioxins (PCDDs), dibenzofurans (PCDFs), and biphenyls (PCBs) were studied by the quantum chemical methods of HF/6-311++G(d,p), B3LYP/6-311++G(d,p), and MP2/cc-pVTZ. The calculated stabilities and structures of these compounds were compared with the available data on their abundance and toxicity. Prediction models for trends in energy and planarity among these congeners were proposed. The results discussed here can help contribute to the understanding of the role of dioxin-like compounds (DLCs) in the environment.     

Establishing an alternative method for the quantitative analysis of polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans by comprehensive two dimensional gas chromatography-time-of-flight mass spectrometry for developing countries

Comprehensive Gas Chromatography-Time-of-Flight Mass Spectrometry (GC×GC-TOFMS) methodology has been refined for the analysis of polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) in samples with different matrices. This is specifically for application in developing countries where access to gas chromatography-high resolution mass spectrometry (GC-HRMS) and highly skilled personnel is limited. The method, using an Rxi-5 Sil MS column in the first dimension ((1)D) coupled with an Rtx-200 column in the second dimension ((2)D), was used to quantify PCDDs and PCDFs in different environmental sample matrices. The results were compared with those obtained using GC-HRMS and good agreement was observed. The limit of detection (LOD) for the method (300fg on column for spiked soil samples) was determined using an Rxi-XLB ((1)D) column coupled with an Rtx-200 column ((2)D). Preliminary South African sample results are also discussed. Isomer specificity for different tetrachloro dibenzo-p-dioxins (TCDDs) and tetrachloro dibenzofurans (TCDFs) was investigated using a commercial standard. Adequate resolution was achieved. The method as described has great attraction for developing countries being both financially and operationally favourable.     

Polychlorinated dibenzodioxins and dibenzofurans in suspended particulate matter of the River Elbe 1994

In April/May 1994 during a period of high discharge in the German part of the River Elbe (9 stations) and its main tributaries (3 stations) samples of suspended particulate matter (SPM) have been collected by means of sedimentation chambers with sampling periods of three or four weeks. Subsequent analyses for polychlorinated dibenzodioxins and dibenzofurans (PCDD/F) have shown that the river enters Germany with a rather low PCDD/F-load which almost steadily increases to below Hamburg. Major sources of contaimination has been the input by the tributary Mulde and resuspension of contaminated sediments along the riversides. Downstream of Hamburg marine influence have caused a sharp decrease of PCDD/F-contents. Changes in the result of 1989, 1992/93 have been discussed.     

Chlorinated organic compounds evolved during the combustion of blends of refuse-derived fuels and coals

The objective of this study was to examine the possible formation of chlorinated organic compounds during the combustion of blends of refuse derived fuels (RDF) and coal under conditions similar to those of an atmospheric fluidized bed combustion (AFBC) system. A series of experiments were conducted using a TG interfaced to FTIR. Additional experiments using a tube furnace preheated to AFBC operating temperatures were also conducted. The combustion products were cryogenically trapped and analyzed with a GC/MS system. The chlorination of phenols and the condensation reactions of chlorophenols were investigated in this study. A possible mechanism for the formation of chlorinated organic compounds such as dibenzodioxins and dibenzofurans, by chlorination and condensation reactions involving phenols, was proposed.The financial support for this work received from the U.S. Department of Energy (Contract No. DE-FG22-94PC94211) and from the Huntsman Thermal Analysis Fellowship is gratefully acknowledged.     

Toxicity of Chlorinated Organic Compounds: Effects of the Introduction of Chlorine in Organic Molecules

Industrial “chlorine chemistry” is accused of polluting the environment with its products and having adverse effects on health. The accusation has been followed by the demand that this ill-defined branch of chemistry be simply abolished, a demand which has been repeated vigorously now for years. It grew out of misgivings such as those summarized here: 1. A number of polychlorinated cyclic compounds are very stable and highly lipophilic so that they accumulate in the environment and affect mankind through the food chain. Prominent examples are chlorinated pesticides, biphenyls, dibenzodioxins, and dibenzofurans. 2. Many chlorinated compounds are toxic for man and animals. Their genotoxicity (mutagenicity and carcinogenicity) plays a role in risk assessment; more and more chlorinated organic compounds are being shown to be carcinogenic and classified accordingly. To date there are no comprehensive reviews of the toxicology of chlorinated organic compounds. The present treatise is the result of an attempt to analyze the situation systematically. It makes generalizations as to the kind and degree of toxicity of the most important classes of chlorinated organic compounds and elaborates recommendations for reduction and avoidance of risk during production, occupational handling, and general use.     

Contributions to the GC-MS-analysis of polyfluorinated dibenzo-p-dioxins (PFDD)

Polyfluorinated dibenzodioxins (PFDD) obtained by synthesis are investigated for their gas chromatographic and mass spectrometric behaviour. Kovats-indices of the investigated PFDD range between 1400 and 1600 on the unpolar column DB5, between 1500 and 1900 on the moderately polar column DB17 and between 2300 and 2800 on the strongly polar SP 2331. Thus PFDD elute between PFB and PCB. As for PCDD the molecular ion peak is the base peak for PFDD, too. However, other than for PCDD the second highest peak is the M-C₂O₂-peak for the lower fluorinated PFDD and the M-COF-peak for the higher fluorinated PFDD (directly followed by the M-C₂O₂-peak). PFDD also show intensive M²⁺-peaks. The intensity of C_xF_y-fragments increases with increasing degree of fluorination.     

Near-ultraviolet femtosecond laser ionization of dioxins in gas chromatography/time-of-flight mass spectrometry

Gas chromatography/multiphoton ionization/time-of-flight mass spectrometry (GC/MPI/TOF-MS) was applied to the trace analysis of polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/Fs). To determine the optimum wavelength for analysis of PCDD/Fs, the wavelength of the femtosecond laser utilized for multiphoton ionization was converted to near-ultraviolet status using stimulated Raman scattering. A femtosecond laser emitting at 300 nm completely eliminated the background signal arising from the bleeding compounds generated from a stationary phase of the capillary column in GC.     

Determination of Polychlorinated Dibenzo-p-dioxins and Dibenzofurans in the Emission from Urban Incinerators

Summary An analytical procedure has been developed for analysis of emissions (ashes, fly ash, fumes and vapours) of urban waste incinerators in terms of their content of the most toxic chlorinated compounds such as polychlorinated dibenzodioxins (PCDD) and polychlorinated dibenzofurans (PCDF). It consists of a selective extraction, a careful clean-up with a silica gel and an alumina column, and gas Chromatographic analysis on high-resolution columns to separate individual constituents of the various classes and detect them with an E. C. detector. Peak identifications were made by comparison with the retention times of reference mixtures and were confirmed by GC-mass spectrometric analysis. It has been found that all emissions contain PCDDs and PCDFs with the more highly chlorinated species predominating. The highest concentration is found in the fly ash, in the range of about 1 ppm total PCDD, and 0.5 ppm total PCDF. It is shown that the formation of these compounds is due to thermal synthesis in the incineration process from precursors in the waste (phenols and chlorinated species).

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Bestimmung poly chlorierter Dibenzo-p-Dioxine und Dibenzofurane in den Emissionen städtischer Müllverbrennungsanlagen

Zusammenfassung Eine Methode zur Analyse von Emissionen städtischer Müllverbrennungsanlagen (Asche, Flugasche, Dämpfe und Abgase) wurde im Hinblick auf deren Gehalt an hochtoxischen chlorierten Verbindungen, wie PCDD (polychloriertes Dibenzodioxin) und PCDF (polychloriertes Dibenzofuran) entwickelt. Die Methode beruht auf einer selektiven Extraktion, einem Reinigungsschritt mit Hilfe einer Silicagel- und einer Aluminiumoxidsäule und letztlich einer gaschromatographischen Analyse. Die GC-Trennung erfolgte mit Hochleistungssäulen, um eine Trennung der zu analysierenden Komponenten für die Erfassung mit einem E.-C.-Detektor zu ermöglichen. Die Identifizierung der Peaks wurde durch Vergleich der Retentionszeiten von Referenzproben durchgeführt und durch GC-MS-Analyse bestätigt. In allen Emissionen wurden PCDDs und PCDFs bei Anreicherung der höher chlorierten Spezies gefunden. Höhere Konzentrationen traten in der Flugaschenprobe mit Gehalten von etwa 1 ppm Gesamt-PCDD und 0,5 ppm Gesamt-PCDF auf. Die Bildung dieser Verbindungen wird auf eine Synthese bei der thermischen Reaktion unter den Prekursoren beim Verbrennungsprozeß (u. a. Phenole und chlorierte Verbindungen) zurückgeführt.

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Presented at the 8th International Microchemical Symposium, Graz, August 25–30, 1980.     

Characterization of military fog oil by comprehensive two-dimensional gas chromatography

The most commonly used military fog oil is characterized by comprehensive two-dimensional gas chromatography (GC×GC) coupled to either Flame Ionization Detection (FID) or Time-of-Flight Mass Spectrometric Detection (TOFMS) to advance the knowledge regarding the complete chemical makeup of this complex matrix. Two different GC×GC column sets were investigated, one employing a non-polar column combined with a shape selective column and the other an inverse column set (medium-polar/non-polar). The inverse set maximizes the use of the two-dimensional separation space and segregates aliphatic from aromatic fractions. The shape selective column best separates individual polycyclic aromatic hydrocarbons (PAHs) from the bulk oil. The results reveal that fog oil (FO) is composed mainly of aliphatic compounds ranging from C₁₀ to C₃₀, where naphthenes comprise the major fraction. Although many different species of aromatics are present, they constitute only a minor fraction in this oil, and no conjugated PAHs are found. The composition of chemically similar aliphatic constituents limits the analytical power of silica gel fractionation and GC–MS analysis to characterize FO. Among the aliphatic compounds identified are alkanes, cyclohexanes, hexahydroindanes, decalins, adamantanes, and bicyclohexane. The aromatic fraction is composed of alkylbenzene compounds, indanes, tetrahydronaphthalenes, partially hydrogenated PAHs, biphenyls, dibenzofurans and dibenzothiophenes. This work represents the best characterization of military fog oil to date. As the characterization process shows, information on such complex samples can only be parsed using a combination of sample preprocessing steps, multiple detection schemes, and an intelligent selection of column chemistries.     

Formation of polychlorinated dibenzodioxins and dibenzofurans by heating chlorophenols and chlorophenates at various temperatures

Summary Polychlorinated dibenzodioxins (PCDD) and polychlorinated dibenzofurans (PCDF) are formed by pyrolysis of chlorophenols and chlorophenates. Under certain conditions the PCDD pattern is completely governed by the chlorine substitution of the starting molecules. Pyrolyses of chlorophenols at elevated temperatures, however, lead to complex PCDD/PCDF mixtures. Nearly all trito heptachlorodibenzodioxin and -dibenzofuran congeners can arise simultaneously from a mixture of only two trichlorophenols. In this case the substitution pattern of the products is no longer influenced by that of the chlorophenols used.

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Bildung von polychlorierten Dibenzodioxinen und Dibenzofuranen durch Erhitzen von Chlorphenolen und Chlorphenolaten bei verschiedenen Temperaturen

Zusammenfassung Polychlorierte Dibenzodioxine (PCDD) und polychlorierte Dibenzofurane (PCDF) werden durch Pyrolyse von Chlorphenolen und Chlorphenolaten gebildet, wobei unter bestimmten Bedingungen das PCDD-Muster vollständig von der Chlorsubstitution der Ausgangsmoleküle bestimmt wird. Die Pyrolyse von Chlorphenolen bei höheren Temperaturen führt jedoch zu komplexen PCDD/ PCDF-Gemischen. Fast alle Tribis Heptachlordibenzodioxine und -dibenzofurane können gleichzeitig aus einer Mischung von nur zwei Trichlorphenolen hervorgehen. In diesem Fall wird das Substitutionsmuster der Produkte nicht mehr von dem der eingesetzten Chlorphenole beeinflußt.

     

Micropore-free surface-activated carbon for the analysis of polychlorinated dibenzo-p-dioxins-dibenzofurans and non-ortho-substituted polychlorinated biphenyls in environmental samples

2,3,7,8-Substituted polychlorinated dibenzo-p-dioxins/polychlorinated dibenzofurans (PCDD/Fs) and non-ortho-substituted polychlorinated biphenyls (PCBs) account for almost all of the total toxic equivalents (TEQ) in environmental samples. Activated carbon columns are used to fractionate the samples for GC-MS analysis or bioassay. Micropore-free surface-activated carbon is highly selective for PCDD/Fs and non-ortho-PCBs and can improve the conventional activated carbon column clean-up. Along with sulfuric acid-coated diatomaceous earth columns, micropore-free surface-activated carbon provides a rapid, robust, and high-throughput sample preparation method for PCDD/Fs and non-ortho-PCBs analysis.